Semisubmersible motor pump



A. HOLLANDER SEMISUBMERSIBLE MOTOR PUMP Filed Sept. 12, 1958 Alada r Hollander INVENTOR 1%r4 84M ATTORNEY Patented Apr. 9, 1940 UNITED STATES PATENT OFFICE Byron Jackson 00.,

Huntington Park, Calif" .a corporation of Delaware Application September 12, 1938, Serial No. 229,508

6 Claims.

This invention relates generally to motordriven deepwell pumps, and particularly to pumping units of the type wherein the motor and pump are suspended within the well from the discharge a column, the pump being positioned below the normal pumping level and the motor being above the highest standing level of the well liquid.

Totally submersible motor pump units such as are in general use at the present time have many l0 advantages over shaft-driven deepwell pumps wherein the motor is located at the top of the well. Aside from the advantages derived from the elimination of the long drive shaft, the motor housing is cooled by the flow of well liquid 13 thereover, and in those motors which operate in an oil-filled housing the heat transfer to the motor housing is more efl'ective. However, such motors are relatively expensive because of the necessity of taking the greatest precaution to 20 avoid leakage of well liquid into the motor housing A principal object of this invention is to provide a motor pump unit having most of the advantages of a fully submersible unit while reducing the cost thereof by eliminating the necessity of providing a perfect seal against entrance of well liquid. This object is attained by mounting the motor in the pump discharge column at a point above the maximum standing level of the well liquid, and by providing an arrangement whereby the motor housing is filled with a liquid oi high dielectric strength and high heat conductivity.

Oil-filled submersible motors are almost invariably disposed below the pump in order that the rotor shaft project from the upper end of the motor housing, the principal reason for this being that a satisfactory seal for a downward'y projecting shaft has not been developed.

A still further object of this invention is to provide an oilfil1ed motor for deepweil motor pump units in which the motor shaft extends downwardly from the motor, and in which the possibllity of leakage of oil from the housing is avoided completely.

Other objects and advantages will be apparent from the following description of one embodiment of the invention, taken in conjunction with the accompanying drawing wherein:

Fig. 1 is a longitudinal sectional view of the upper portion of a motor pump unit constructed in accordance with this invention and installed in a well; and

Fig. 2 is a view, partly in elevation and partly in longitudinal section, of the lower portion of the unit.

Referring to the drawing, reference numeral I indicates a pump discharge column extending downwardly from the surface of a well which is lined with casing 2. Secured to the lower end of the column I is a slightly eccentric reducer and flange fitting 3 to which is secured an outer casing 4. The lower end of the casing 4 is substantially closed by the flange portion 5 of a fitting 6 connected between the casing and a lower discharge column 1, usually of considerable length. A conventional deepwell centrifugal pump I0 is connected to the lower end of the column I by means of the usual discharge piece II.

It will be noted that the casing 4 is positioned above the maximum standing level of the well liquid, as indicated at I 5, so that the motor housing within the casing 4 is always above the well liquid. The length of the fitting 6 and the lower discharge column I is greater than the maximum normal draw-down of the well, so that the pump I0 is disposed below the normal pumping level of the well liquid, as indicated at I 6.

An upstanding annular flange 20 is formed integral with the flange portion 5 of the fitting 6, and has mounted thereon a reservoir 2| of smaller diameter than the casing 4 to form an annular discharge channel 22 therebetween. A motor housing 23 is mounted on the upper end of the reservoir in fluid-tight relation thereto, the upper end of the housing being closed by a cap 24. The motor housing and oil reservoir are thus disposed in the discharge column in heat exchange relation to the stream of discharge liquid.

An electric motor 21 is mounted in the motor housing 23, the rotor 28 being rotatably supported in an upper bearing 29 and a lower bearing 30. The upper bearing is mounted in a bracket 3| bolted, to the stator frame, and the lower bearing is mounted in a bracket 32 formed integral with the upper end of the reservoir 2|, the lower end of the stator frame being bolted to the bracket 32. A bolt 33 is threaded into the upper bracket 3| and passes through the cap 24, the outer end of the bolt being engaged by a nut 34. A gasketed washer 35 is interposed between the nut 34 and the cap 24 for sealing, around the bolt. By tightening the nut, the cap 24 is drawn tightly against the upper end of the motor housing, compressing the confined packing 36, and the motor housing is forced down against the lower bracket 32, compressing the packing 31.

Electrical energy is supplied to the motor from u the surface through a conductor cable 4| which enters the casing 4 through a pothead 4i. The pothead is secured in fluid-tight relation to a tubular extension 42 formed integral with the cap 24 and projecting through an opening in the flange portion 43 of the fltting I in fluid-tight relation thereto. Within the pothead 4| the terminals of the conductors in the cable are secured to the upper terminals of a short length of cable 44 connected at its lower end to the motor windings. I

It is desirable that the motor housing be fliled with a dielectric liquid, at least while running, to aid in dissipating the heat generated by the motor. It is well recognized that the rate of dissipation of heat from the motor through the housing to the stream of discharge liquid is much higher in an oil-fllled motor than in an air-fllled motor. However, difficulties have been experienced in prior attempts to provide an oil-fllled motor when the rotor shaft projects through the lower end of the motor housing, due to the leakage of oil from the housing through the stuffing box around the shaft. I have overcome these difficulties by the arrangement described below.

The lower end of the reservoir is closed by a plate 45 formed integral with an upstanding sleeve 49 extending nearly to the upper end of the reservoir and closely surrounding the rotor shaft 50. The plate 40 is secured in fluid-tight relation to the reservoir II by a confined gasket 5i compressed by a nut 52 threaded to the lower end of the reservoir, to prevent leakage of well liquid from the discharge channel 22 into the reservoir. An annular reservoir is thus formed which normally contains 011 or other dielectric liquid up to the level indicated at 53 when the motor is idle. A close-fitting, machined sliding fit is provided at 54 between the lower end of the reservoir and the upstanding flange 25, accurately centering the reservoir on the flanged fltting I and sealing of! the discharge channel 22 from the interior of the flange 20.

An inverted sleeve member 55 is secured at its upper end in fluid-tight relation to the shaft 52 and extends downwardly around the sleeve 5| to adjacent the lower end of the reservoir. A

pinion 51 is keyed to the shaft 5| above the sleeve 55 and meshes with a pinion 58 keyed to a shaft 59 journaled .at its upper end in the bracket 32. The lower end of the shaft extends downwardly to a small pump 50, preferably a gear pump, mounted on the base plte 48. The inlet of the pump communicates with the reservoir 2| and connected to the discharge outlet thereof is a conduit 6| extending upwardly to the upper motor bracket 3|, being connected thereto at 62 above the upper bearing 29. A baffle 63 is secured to the shaft 52 between the pinion 51 and the lower bearing 30, the baiile forming with the inner wall of the bracket 32 a throttle passage 84 restricting the drainage of oil from the motor housing back to the reservoir. A port 81 is formed in the flange 5 at the base of the casing 4 to establish communication between the air space of the well and the reservoir, whereby the latter is at atmospheric pressure.

The shaft'52 is journaled in a bearing bushing 68 in the flange 5, and extends downwardly to the pump. Surrounding the shaft between the fitting 6 and the discharge piece is a tube 10 for conducting lubricant to a sleeve bearing 1| in the discharge piece. A lubricant conduit 12 extends from the surface to a nut I3 to which the tube 10 is secured.

fol-

bearing 2. the oil works its way downwardly around andthroughtherotorgaptothelowerbearingll through is lea than the discharge capacity of the gear pump I, and consequently the oil gradually collects above the bearing 8. and eventually fllls the motor housing, the oil level in the reservoir being lowered to substantially the level indicated at II. A dynamically balanced condition is then established, the increased static pressure of the oil in the motor housing causing it to flow through the throttle passage at a faster rate than initially.

Assoonasalayerofoilcollectsabovethe lower bearing 8|, the air in the motor housing would be entrapped therein, and would prevent filling the motor homing completely with all. To avoid this an air vent tube IO extends from the upper end of the motor housing downwardly in the space between the stator shell and the housing and through the bracket 32 into the reservoir. This allows the complete interchange of oil and air between the motor housing and the reservoir, and provides an oil overflow when the oil level reaches the upper end of the vent tube.

It will be observed that the outer sleeve 55 dips into the oil in the reservoir at all times to provide a liquid seal preventing the admission of moisture-laden air from the well into the reservoir and thence into the motor housing. The inverted sleeve '5 also insures that none of the oil draining back to the reservoir enters the inner sleeve 45.

From the foregoing description it will be evident that I have provided a semisubmersible motor pump lmit which v. a. most of the advantages of a totally submersible unit but which is relatively inexpensive as compared to submersible units. Effective cooling of the motor and lubrication of the is provided by the continuous forced circulation of oil, and there is no danger of 10s of oil such as is likely to occur through a stufling box around the shaft. The pump shaft need be of a length only slightly greater than the normal draw-down of the well, as compared to a shaft several hundred feet in length when the pump is operated by a motor at the surface.

I claim:

1. A semisubmersible motor comprising a substantially vertically extending housing having a fluid-tight closure at its upper end and a base having a centrally dispoud shaft opening therein, an electric motor mounted in the upper portion of said housing and having a shaft extending downwardly through the shaft opening in said base, a sleeve extending upwardly from said base in substantially concentric relation to said shaft and defining with the walls of said housing an annular reservoir containing a dielectric liquid,

a pump driven by said shaft for transferring liquid from the reservoir upwardly to said motor, and means between the motor and reservoir forming a restricted passage affording restricted flow of liquid from said motor back to said reservoir.

2. A semisubmersible motor comprising a substantially vertically extending housing having a closed upper end and a base having a shaft opening therein, an electric motor mounted in the upper'portion of said housing and having a shaft extending downwardly through said shaft opening into operative engagement with a driven element outside of and below said housing, said base having a sleeve extending upwardly from said shaft opening in substantially concentric relation to said shaft to define an annular reservoir for dielectric liquid in the lower portion of said housing, a pump driven by said shaft for transferring dielectric liquid from the reservoir upwardly to said motor, means between the motor and reservoir forming a restricted passage affording flow of liquid at a restricted rate from said motor back to said reservoir, and a baille beneath saidrestricted passage and overlying the space between said shaft and said sleeve.

3. A semisubmersible motor comprising a housing having a closed upper end and a base having a shaft opening therein, a partition extending transversely of said housing and dividing the latter into upper and lower compartments, an electric motor mounted in the upper compartment and having a drive shaft extending downwardly through said partition, lower compartment, and shaft opening, a sleeve extending upwardly from the base of said lower compartment in substantially concentric relation to said shaft and forming an annular reservoir, and means for maintaining said motor compartment substantially filled with dielectric liquid during, and only during, operation of the motor, comprising a supply of dielectric liquid normally maintained in said reservoir when said motor is idle, a pump driven by said shaft for transferring said liquid to said motor compartment during operation of the motor, and a restricted passage in said partition aflording restricted flow of said liquid back to said reservoir.

4. A semisubmersible motor as set forth in claim 3, in which said housing is mounted within an outer casing adapted to form part of a well discharge column whereby the walls of said housing are cooled by flow of well fluid past said housing.

5. A semisubmersible motor as set forth in claim 3, in which said housing is mounted within an outer casing adapted to form part of a well discharge column whereby the walls of said housing are cooled by flow of well fluid past said housing, the base of said housing being sealed in fluidtight relation to said casing and the shaft opening in said base being in open communication with the exterior of said casing.

6. In combination in a semisubmersible structure, a substantially vertical housing having a transverse partition dividing it into an upper compartment and a lower compartment, a rotatable element insaid upper compartment and a shaft connected to said element and extending downwardly through said partition and through said lower compartment, a sleeve extendingupwardly from the base of said lower compartment in substantially concentric relation to said shaft and forming an annular reservoir, and means for maintaining said upper compartment substantially filled with lubricant during, and only during, rotation of said shaft, said means comprising a supply of lubricant normally maintained in said reservoir when said shaft is idle, a pump driven by said shaft for transferring lubricant upwardly to said upper compartment during operation of said shaft, and a restricted passage in said partition affording restricted flow of said lubricant back to said reservoir.

ALADAR HOLLANDER. 

